The invention is a method for incorporating peripheral printers within a data processing system whereby the number of printer control commands required is reduced.
Currently, printers use different sets of commands for the downloading of bitmap graphics and bitmap font glyphs. The disclosure herein is a simplification of the current process by downloading and then printing bitmap graphics using the same set of printer control commands that are used to download and print bitmap font glyphs.
Soft font data and graphic images are stored on a host computer in a variety of formats. These data formats are converted to the printer control language by an application program and/or a printer driver running on the host. Currently, graphics images are converted to a special bitmap graphic format comprised of a group of printer commands designed for bitmap graphics printing and the bitmaps for each glyph in a soft font are converted to a different format comprised of another group of printer commands designed for downloading soft fonts.
The present invention overcomes the limitation of the prior art by streamlining the process. Streamlining is accomplished by using the same printer commands to download and print both graphics and fonts. The inventive step thus simplifies the firmware required in a selected printer and allows the use of a slower and less expensive microprocessor to drive a given application. Additionally, printer ROM memory can be reduced or freed up for other tasks, and RAM memory can be increased to handle more detailed data.
U.S. Pat. No. 5,150,456 for a GRAPHIC IMAGE PRINTING SYSTEM AND METHOD, issued Sep. 22, 1992 to Wu et al. discloses a high speed, low cost real time graphic image printing system which includes a host data processing system, a laser printer having a plug connector for receiving a font cartridge storing information defining an image of a printable character, and a cartridge pluggably connected to the font cartridge plug connector. A first communication path carries print commands from the host to the printer while a second communication path carries image defining information between the host and the data store. In operation, the host writes information defining a portion of an image to be printed into a portion of the data store corresponding to a selected character and then commands the printing of the selected character. A ping-pong double buffer arrangement allows the host to write a next image portion while information defining a current image portion is read by the printer to form a print image.
The current invention obviates the requirement of Wu et al. for using two communication paths. The result is a cheaper, more efficient, system that is commercially viable.
U.S. Pat. No. 4,520,455 for a PRINTING SYSTEM, issued May 28, 1985 to Crean et al., discloses the use of two buffers employed so that while the contents of one buffer are used to control the printer, the second buffer can be bit formatted under microprocessor control. And, while this configuration provides efficiency in that the signals representing desired print characters and the commands to the printer to actually print the characters are stored separately and can thus function independently; the downloading of graphics and/or fonts to the printer still require that the printer commands for the graphics be different from that of the fonts.
Printer controllers which control a printer shared with plural data processors are disclosed in U.S. Pat. No. 5,068,807 for a PRINTER CONTROLLER, issued Nov. 26, 1991 to Ikenoue. In this disclosure, as with others in the art, the printer commands follow two paths; that is, there are separate printer commands to download and print graphics or fonts.
U.S. Pat. No. 5,337,258 for COST METRICS, issued Aug. 9, 1994 to Dennis, discloses the use of separate printer commands to describe the transfer of font glyphs then are used when transferring bitmaps.
An object of the present invention is to overcome the limitations of the prior art by providing a method for printing that reduces unnecessary or duplicative command requirements in printing bitmapped graphic images.